Depression Tied to Mental Loss in Parkinson's

by Ed Susman Contributing Writer, MedPage Today

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Note that this study of patients with Parkinson's disease and healthy controls demonstrated a strong association between mild cognitive impairment and worse scores on standardized tests for depression and anxiety.

Be aware that the cross-sectional nature of the study precludes a formal assessment of causality.

SYDNEY -- Nonmotor symptoms such as depression and anxiety appear to be more frequent among patients with Parkinson's disease who also are diagnosed with mild cognitive impairment, researchers reported here.

In comparing scores on the Beck Depression Inventory II, patients with Parkinson's disease and mild cognitive impairment registered a mean score of 14.6; those patients with Parkinson's disease but without mild cognitive impairment scored 8.6, while healthy controls scored 5.3 (P<0.05 for all comparisons), said Sabrina Diab, MS, a PhD candidate at the Center for Advanced Research in Sleep Medicine at the Hôpital du Sacre-Coeur in Montreal.

In addition, patients with Parkinson's disease and mild cognitive impairment scored an average of 14.1 on the Beck Anxiety Index, which was statistically significant compared with Parkinson's disease patients without mild cognitive impairment (5.9) and controls (4.1) (all comparisons, P<0.05), Diab said at her poster presentation at the International Congress on Parkinson's Disease and Movement Disorders.

The 5.9 score is below the cut-off for clinical anxiety, Diab said, so while it is statistically significant, it might not be clinically meaningful. She noted the results were significant despite small numbers of patients in each group.

"What we found is that patients who have Parkinson's disease and mild cognitive impairment scored higher on those scales of depression and anxiety versus patients with Parkinson's disease and without mild cognitive impairment, and versus the control group as well," she said. "We think that if you are treating a Parkinson's disease patient with mild cognitive impairment, that person is more likely to have depression and anxiety."

For the study, Diab and colleagues recruited 36 patients with Parkinson's disease who were taking only dopaminergic medications. They diagnosed 16 of those patients with mild cognitive impairment. The patients with Parkinson's disease were compared with 36 healthy controls.

Most of the participants in the trial were men, and their average age was about 65 years. Disease duration was 6.4 years in the Parkinson's patients with mild cognitive impairment compared with 4.3 years for those without cognitive impairment, but that difference was not statistically significant.

When the researchers scrutinized results on measures of sleep, Diab said, "What we have also seen is that patients with Parkinson's disease and mild cognitive impairment, and Parkinson's disease without mild cognitive impairment, scored higher on the Epworth Sleepiness Scale and the Insomnia Severity Index versus the control group.

"For now, we think that mood symptoms are more related to cognitive impairment, and sleeping complaints are more related to Parkinson's disease."

The researchers did not evaluate the type or severity of the depression or of the anxiety disorder.

Alison Yarnall, MD, of the University of Newcastle in England, told MedPage Today, "This is an interesting pilot study, but we need more information. The numbers in this study are small and only 16 of the patients have mild cognitive impairment."

"Anxiety and depression can impact the tests we do for cognitive impairment, so we should take these results with a pinch of salt because it is kind of chicken or egg," commented Yarnall, who did not participate in the study. "Do people with mild cognitive impairment have more depression and anxiety or is their depression and anxiety impairing their testing abilities? We need a larger study to help us tease out what is really happening with these patients."

Diab and Yarnall had no disclosures.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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